The query string consists of the parameters following the URL. For example, if the client's browser was directed at
http://servername/webname/pagename.csp?paramName=paramValue, the query string would be paramName=paramValue.
ok，明白了，本质就是获取带参数查询。
String queryString = request.getQueryString();
queryString = new String(queryString.getBytes("ISO-8859-1"));
String str = queryString.replaceAll("[\\p(ASCII)]","");
String encode_cn = URLEncoder.encode(str,"gbk");
queryString = queryString.replaceAll(str,encode_cn);
Returns the query string that is contained in the request URL after the path，
post方法传的参数，getQueryString（）得不到，
它只对get方法得到的数据有效。
